Forensic Science Study Guide Chapter 6 Fibers Name:______
1. Why are fibers considered class evidence?
They can’t be traced back to an individual.
2. Fabric is made of __fibers______. Fibers are made of twisted ___filaments______.
3. What are the 2 type of fibers and fabric?
Natural, artificial
4. Name 6 types of synthetic fibers:
Rayon,Nylon, Acetate, Acrylic, Spandex, Polyester
5. Name 5 types of natural fibers:
Silk, cotton, wool, Mohair, Cashmere
6. Natural fibers are classified according to their __origin______:
a. Vegetable or cellulose
b. Animal or protein
c. Mineral
7. Cellulose fibers:
Cotton—vegetable fiber; strong, tough, flexible, moisture-absorbent, not shape-retentive
Rayon—chemically altered cellulose; soft, lustrous, versatile
Cellulose acetate—cellulose that is chemically altered to create an entirely new compound not found in nature
8. Protein fibers:
Wool—animal fiber coming most often from sheep, but may be goat (mohair), rabbit (angora), camel, alpaca, llama, or vicuña
Forensic Science Study Guide Chapter 6 Fibers Name:______
Silk______—insect fiber that is spun by a silkworm to make its cocoon; the fiber reflects light and has insulating properties
9. Mineral Fibers:
a. Asbestos—a natural fiber that has been used in fire-resistant substances
b. Rock wool—a manufactured mineral fiber
c. Fiberglass—a manufactured inorganic fiber
10. Synthetic Fibers : Made from derivatives of petroleum, coal, and natural gas.
11. a. Nylon—most durable of man-made fibers; extremely lightweight
b. Polyester—most widely used man-made fiber
c. Acrylic—provides warmth from a lightweight, soft, and resilient fiber
d. Spandex—extreme elastic properties
12. Weave terminology:
Yarn—a continuous strand of fibers or filaments that may be twisted together
Warp—lengthwise yarn
Weft—crosswise yarn
Blend—a fabric made up of two or more different types of fibers
13. Weave Patterns:
a. Plain
Forensic Science Study Guide Chapter 6 Fibers Name:______
b. Satin
c. Twill
14. Which weave is the most common pattern?
Plain weave
15. Which design resembles a stair steps?
Twill
16. Denim is an example of what weave pattern?
Twill
17. In which weave pattern does the warp yarn is pass over one to three weft yarns before going under One? Twill
18. ____Knitting______are made by interlocking loops into a specific arrangement. It may be continuous thread or a combination.
Forensic Science Study Guide Chapter 6 Fibers Name:______
19. Synthetic fibers are made of polymers, which are long chains of repeating chemical units.
20. The word __polymer______means many units.
21. Filament Cross Sections:
R ound 4-
Octalobal T rilobal Irregular
Dogbone or Multi- Dumbbell or 21.
22. Testing for identification: a. Density______—the mass of an object divided by the volume of the object b. Refractive index—measurement of the bending of light as it passes from air into a solid or liquid c. Fluorescence—absorption and reemission of light; used for comparing fibers as well as spotting fibers for collection
Forensic Science Study Guide Chapter 6 Fibers Name:______
23. There are more than 7,000______different dye formulations.
24. Chromatography is used to separate dyes for comparative analysis.
25. Collection of fiber evidence:
Bag clothing items individually in paper bags. Make sure that different items are, are not placed on the same surface before being bagged.
Make tape lifts of exposed skin areas and any inanimate objects.
Removed fibers should be folded into a small sheet of paper and stored in a paper bag.
26. Wayne Williams was convicted in 1982 based on ___carpet Fibers______that were found in his home, in his car, and on several murder victims.